a motorcyclist drives from a to b with the uniform speed of 30 km/h-1 and returns back with the speed of 20 km/h-1.find the average speed?

If 2 moles of co_2 at 2l and 500k are expanded reversibly to 20l, more work can be obtained from an adiabatic process than from an isothermal process. is the above statement true or false?

Aweight lifter raises a 1600 n barbell to a height of 2.0 meters. how much work was done? w = fd a) 30 joules b) 3000 joules c) 320 joules d) 3200 joules

4.at 0 ºc, some amount of energy is required to change 1 kg of water from a solid into a liquid. if you had a 2 kg piece of ice, what effect would this have on the amount of thermal energy required to change the water from a solid to a liquid? it would require more energy to change solid water into liquid water because there are more molecules in this larger piece of ice. it would still require the same amount of energy to change solid water into liquid water because the entire piece of ice would still gain the same amount of energy in each case. it would require energy to be removed from the 2 kg piece of ice. the larger piece of ice already has more total energy than the smaller piece of ice, so energy must be removed for the ice to become liquid. it would require less energy to change solid water into liquid water because the energy would spread through the ice more quickly and the ice already has a larger total amount of energy because it is larger than a 1 kg piece of ice.